John Morton, director of Immigration and Customs Enforcement, said the sites were seized over the past few days and that most of the goods were manufactured in China. Internet users trying to access the sites now are greeted with a message from the government that the domain name has been seized and that willful copyright infringement is a crime.

“The basic emphasis is simple: We want to promote a lawful online environment as much as we can, and that means going after the small but significant (number) of websites engaged in frauds on consumers,” Morton said in a conference call with reporters.

Among the domain names seized were Autocd.com, DVDshopdvd.com and DVDsetonline.com. Most were sites selling NFL and other sports apparel.

The seizure is the latest phase of Operation in Our Sites, a coordinated effort by ICE, the Justice Dept. and the FBI’s Washington field office to stem the flow of counterfeit and pirated goods. The operation is coordinated by the National Intellectual Property Rights Coordination Center. Since the launch in 2010, a total of 350 domain names have been seized, and the seizure banners have received more than 77 million views.

Morton said that investigators identified the goods by making undercover purchases from the sites and confirming with the owner of the copyright that they are fake. The sites have 60 days to challenge the seizure warrants, and although Morton said that most never do, the seizures have been criticized by digital rights groups, saying that they raise due process and First Amendment concerns because site owners who believe their sites have been mistakenly seized have little recourse to prevent a halt in their operations.

Two bills pending in Congress are aimed at stemming the flow of pirated material online from sites with domain names registered in other countries.

Morton added that they are investigating organized crime’s links to the sale of counterfeit goods. “This is increasingly not a matter of mom and pop violations at the corner of Fourth and Main,” he said.

Although sites can relatively easily pop up again by changing their domain names, the seizures “disrupts that supply of customers and the advertising base,” Morton said.

Meanwhile, on Tuesday, Attorney General Eric Holder and other administration officials will hold a press conference at the White House to elaborate on the administration’s efforts to crack down on piracy and to launch a new public awareness campaign.